The present invention is directed to apparatus designed to mount tubeless tires on automotive vehicle wheels in a production line environment. Such machines are employed in vehicle assembly plants and must be capable of operation at a production rate which will supply sufficient assembled wheels and tires at a rate dictated by the speed of the vehicle production line.
In a typical tire-wheel assembly line, the wheels are mounted on a pallet conveyor which advances the wheels in step by step movement through a series of work stations. At a point on this conveyor line upstream from the tire mounter, a tire is rolled onto each pallet from one side of the conveyor into a position on the pallet immediately in front of the wheel. The tire arrives on the pallet in a vertical position and is subsequently knocked backwardly into a rearwardly inclined position on the wheel in which the lower bead of the tire rests on two circumferentially spaced points on the uppermost rim flange of the horizontally positioned wheel.
In a typical prior art mounting operation, the wheel and tire are then advanced beneath a horizontal roller which extends transversely of the conveyor above the level of the uppermost rim flange of the wheel. This roller forces the beads of the tire downwardly below the rim flange as the wheel and tire pass beneath the roller.
This brute force approach results in an intense abrasive action on the beads. The normal diameter of the opening defined by the beads must be smaller than the outer diameter of the rim flange and hence the beads are violently distorted and subject to substantial frictional forces as they are pressed downwardly to pass the rim flange. The problem is particularly acute in the case of relatively wide tread low profile tires.
In an effort to address this problem, it has been proposed, see U.S. Pat. No. 4,621,671, to mount only one bead of the tire on the wheel at a time. In the apparatus of U.S. Pat. No. 4,621,671, the lowermost bead of the tire is forced over the rim flange at a first work station and the uppermost bead is then forced onto the wheel at a subsequent work station. In this apparatus, during the mounting of the lowermost bead, the upper bead acts as a cushioned force transmitting element between the roller and lower bead and is able to transmit this force efficiently because the upper bead is not engaged with or restrained by the rim flange during the mounting of the lower bead.
While the single bead mounting procedure employed in the apparatus of U.S. Pat. No. 4,621,671 represents a substantial improvement over the prior art practice of forcing both beads onto the rim at the same time, it has not completely eliminated the adverse effects generated by the forcing of a bead of a first diameter downwardly over a rim of larger diameter.
The present invention is directed to a solution to this problem in which a single bead mounting approach is applied in a manner which minimizes stretching of the tire bead being mounted and frictional forces exerted between the wheel rim and bead during the mounting operation.